The development of cell mediated immunity (CMI) in patients with bladder carcinomas against their own tumor and other tumors of the same cell type has been demonstrated. If the tumor is actively growing, "blocking factor" against this CMI may be shown. We propose to follow the development of CMI and blocking factor in conjunction with the normal cystoscopic and urine cytology follow-up that these patients would normally have. The immediate goal is to determine if the blocking factor appears early in the development of the tumors so that it could be used as a technique of following the patients for small early recurrences. An animal model of bladder tumors has been developed which will be studied in parallel with the patients to determine the effect various manipulations (i.e. removal of the tumor) will have upon the host immunological response to that tumor. It is hoped that the further understanding of the host reaction to these tumors will eventually lead to some form of immunotherapy as well as being useful in diagnosis.